A technique for encoding a signal used in a digital communication system in which individual traffic channel data rates may be adapted to specific channel conditions. In particular, a forward error correction coding rate is adapted for individual channels while at the same time maintaining a fixed block size independent of the FEC coding rate. This allows the system data rate to adapt to the channel conditions experienced by a specific user. Thus, users experiencing good communication conditions with low multipath distortion may be allocated higher capacity, whereas users with significant multipath distortion may make use of lower rate (higher levels of coding) error codes to maintain high quality. Messages are sent from a transmitter to a receiver to inform the receiver of the coding rate implemented at any given point in time. These parameters may be adjusted independent of transmitted power level through the expedient of ensuring that size of a transmitted frame remains constant, while permitting the ability to change FEC coding rates and FEC block sizes.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A subscriber unit comprising: a forward error correction (FEC) encoder configured to encode each of a plurality of frames, each of the plurality of frames including a variable number of data bits, to include an error correction code such that a resulting number of output encoded bits is fixed, and to include the error correction code such that the resulting number of output encoded bits is fixed by varying a coding rate of the FEC encoder.
2. The subscriber unit of claim 1 , further comprising: a modulator configured to modulate the output encoded bits according to a multiple-access modulation technique to produce a modulated encoded signal.
3. The subscriber unit of claim 1 , wherein the FEC encoder is configured to encode each of the plurality of frames according to a coding rate that changes during a wireless connection of the subscriber unit, and wherein the coding rate is one of a ¼ code rate, a ⅓ code rate, a ½ code rate, or a ⅞ code rate.
4. The subscriber unit of claim 1 , wherein one of the plurality of frames is selected to produce, when encoded, a desired number of output bits in an encoded frame.
5. The subscriber unit of claim 1 , further comprising: a processor configured to provide a coding rate select signal; wherein the FEC encoder includes the error correction code based on the coding rate select signal.
6. A subscriber unit comprising: a forward error correction (FEC) encoder configured to receive data bits and to generate frames, each frame having a predetermined length and an error correction code, wherein the predetermined length of each frame is fixed as a number of the data bits varies; and a processor configured to generate a coding rate select signal; wherein the FEC encoder encodes the frames based on the coding rate select signal.
7. The subscriber unit of claim 6 , further comprising: a modulator configured to modulate each frame according to a multiple-access modulation technique to produce a modulated encoded signal.
8. The subscriber unit of claim 6 , wherein a coding rate of each frame is one of a ¼ code rate, a ⅓ code rate, a ½ code rate, or a ⅞ code rate and the coding rate changes during a wireless connection used by the subscriber unit.
9. A base station comprising: a forward error correction (FEC) encoder configured to encode each of a plurality of frames, each of the plurality of frames including a variable number of data bits, to include an error correction code such that a resulting number of output encoded bits is fixed, and to include the error correction code such that the resulting number of output encoded bits is fixed by varying a coding rate of the FEC encoder.
10. The base station of claim 9 , further comprising: a modulator configured to modulate the output encoded bits according to a multiple-access modulation technique to produce a modulated encoded signal.
11. The base station of claim 9 , wherein the FEC encoder is configured to encode each of the plurality of frames according to a coding rate that changes during a wireless connection of the base station, and wherein the coding rate is one of a ¼ code rate, ⅓ code rate, ½ code rate, or ⅞ code rate.
12. The base station of claim 9 , wherein one of the plurality of frames is selected to produce, when encoded, a desired number of output encoded bits in an encoded frame.
13. The base station of claim 9 , further comprising: a processor configured to provide a coding rate select signal; wherein the FEC encoder includes the error correction code based on the coding rate select signal.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
September 15, 2008
June 5, 2012
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